Anyone Have Experience With SOT89
Printed From: PCB Libraries Forum
Category: General
Forum Name: General Discussion
Forum Description: general topics not related to other forums
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=1015
Printed Date: 25 Nov 2024 at 3:23am
Topic: Anyone Have Experience With SOT89
Posted By: rickdehart
Subject: Anyone Have Experience With SOT89
Date Posted: 12 Jul 2013 at 3:51pm
I am curious why all recommended footprints for SOT89 seem to allow the pins to overhang on the inside. I fear this could cause shorts.  |
Replies:
Posted By: Tom H
Date Posted: 12 Jul 2013 at 6:01pm
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The SOT89 was one of the first SMT components invented. There is no real industry standard so every mfr. makes their own version. For the Footprint creation I normally add 0.05 mm (2 mils) periphery around the component lead. I don't understand the datasheet link you provided where the component lead is Q = 0.062" but the mfr. recommended pattern has the pad length 0.059" which is smaller than the lead. So I don't trust the datasheet. The VPL only matches a specific mfr. part number with a footprint and there are dozens of different part numbers. You are correct that the footprint in your picture with the VPL lead will short to the copper pour. We have avoided creating a SOT89 component family for the Library Expert because pin 2 is irregular shaped and comes with many variations. This is one of those parts that you create once and never create it again (hopefully). ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |